1. Field of the Invention
The present invention relates to an antenna for a mobile communication terminal and, more particularly, to an inverted-F antenna, in which a feeder and a ground are integrally formed, and a mobile communication terminal using the same.
2. Description of the Related Art
With recent popularization of portable wireless terminals including GPS, PDA, cellular phone and the like, terminals with diverse functions and designs are introduced. In addition, as the terminals have miniaturized and slimmer designs, the importance in diversity of the functions of the terminals has been emphasized more than ever.
In particular, as the conventional rod antenna and helical antenna protrude out of the terminal in a predetermined length, the likelihood of damage is increased when the terminal is dropped, which in turn degrades portability. Therefore, planar internal antennas, which are mounted inside the terminals, have been recently introduced.
The inverted-F antenna is connected vertically to a board, and has a protrusion extending from a longitudinal middle part thereof to be parallel with the board, in which a feeder is connected to a portion of the antenna opposing the board.
FIGS. 1 and 2 are plan views illustrating a conventional inverted F-antenna and a mobile communication terminal using the same, according to the prior art (Korea Patent Application No. 2003-0075469, entitled “Inverted F-Antenna Using FPCB and Mobile Communication Terminal with the Inverted-F Antenna”).
Referring to FIG. 1, the inverted-F antenna 10 has its conductive line 11 disposed in a shape similar to an alphabet ‘F’ on a Flexible Printed Circuit Board (FPCB) 12. The line 11 of the inverted-F antenna 10 has one end connected to a transceiver 13b which is a signal applier. The line 11 extends in a straight line along the longitudinal direction of the FPCB and is bent in a vertical direction, and then is bent in vertical and horizontal directions for multiple times. A matching circuit 11M is formed at the portion of the line 11 extending along the longitudinal direction of the FPCB 12 and connected to the substrate 13a. 
The part where the antenna is bent for multiple times is called a “radiator” 14, which generates a resonant frequency and multi-band according to the interval between the lines 11R, the width of the line 11R and the size of the radiator 14.
This kind of antenna structure, however, has a problem in that bending and mounting the antenna cause changes in the characteristics of the antenna since the signal line and the ground line are made separate from each other.
FIG. 2 is a plan view illustrating the inverted-F antenna disposed on the substrate and mounted in a folder-type mobile communication terminal.
Inside the mobile communication terminal body 28, the inverted-F antenna 10 is installed in parallel with the substrate 25.
This mounting structure of the antenna is mainly focused on reducing the thickness of the terminal, but in practice, as the antenna mounting space occupies a relatively large area, the miniaturization of the terminal is limited. Furthermore, as the antenna is installed in parallel with an RF board, the operation of the antenna is interfered by the terminal body or the metal portions (key pad assembly, LCD module, etc.) of the folder, hindering adequate antenna radiation characteristics.